Joseph a



1. A. MILLER. Hot Air Furnace.

Patented Amal 25, 1865.

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UNITED STATES PATENT OFFICE.

JOSEPH A. MILLER, OF NEV YORK, N. Y.

HOT-AIP. FURNACE.

Specification forming part of Letters Patent No. 47,1143, dated April 25, 1865. i

To @ZZ whoml ,it may concern:

Be it known that l, J osErH A. MILLER, of No. ,200Broadway, in the city, county, and State of New York, have invented a new and useful Improvement in Hot-Air Furnaces; and I do hereby declare that the following is a full, clear, and exact description of the same, reference bein g had to the accompanying drawings, forming part of this specification, in which- Figure l is a central longitudinal vertical sectionof a furnace constructed according to my invention. Fig. 2 is a transverse vertical section of the same.

Similar letters of reference indicate corresponding parts in both figures.

In hot'air furnaces in which air is heated by passing through iron tubes between and around which the flame and gaseous products of combustion circulate on their way from the fue to the chimney, or by passing betweeniron tubes through which the flame and gaseous products of combustion so circulate, the temperature of the air so heated is liable to rapid lluctuations, with variations in the condition of the lire.

The object of the first part of my invention is to obviate this, and to prevent the temperature of the heated air from being so much or so quickly influenced by changes in the condition of the ire and to this end it consists in placing between, among, or within the tubes in the spaces through which the fiame and heated gases circulate lumps of brick or other refractory material which is a poor conductor of heat, and which acts as a heat-receiving medium or heat-reservoir.

The second part of my invention consists in a novel arrangement of fines and airfheating tubes and spaces in relation to each other and to the tire-place, whereby the air circulating upward in contact with heatin g media, in contact with which the heated gaseous products of combustion circulate downward, is heated with a very economical expenditure of fuel.

To enable others skilled in the art to make and use my invention, I will proceed to describe it with reference to the drawings.

A is a shell or casin g of brick-work or other material of a capacity according to the quantity of air to be heated, having the tire-place B at one end. In -rear of the lire-place there is a horizontal fine, C, of the whole width of the shell A, and extending from the bridgewall F of the fire place nearly to the rear end of the said chamber. This flue is formed by two horizontal tubesheets, D D', extending all across the shell A, and these'tube-sheets receive a number of vertical air-tubes, G G, the lower endsof which communicate with the colcl-air chamber H in rear of the ash-pit and below the tube-sheet D', and the upper ends of which communicate with `the hotair-dis tribnting chamber E above the tube-sheet D and lire-place. In rear ofthe tlue G and coldair chamber H, and in communication with the line G, there is a vertical` drop-line, I, from which, just below the fiue C, a pipe-flue, J, extends horizontally forward through the upper part of the chamber H nearly to the front thereof', where it has a downward bend, and from whence it returns in a horizontal direction through the lower part of the said` brick or other poor conducting material, of

such irregular or other shape that interstiees will be left between them for the circulation of thellame and heated gaseous products of combustion on their way from the fire -place tlirou gh the flue C toward the chimney.

At the sides of thecold-airchamber H,close to the bottom thereof, are openings for the ingress of cold air, and at the top of the hot-air chamber E one or more pipes, J J, are provided for conveying the heated air wherever it is to be used.

When the fire is lighted, the flame and gaseous products of combustion pass through the Hue C, thence down the flue I, thence forward, downward, and backward through the flue J to the chimney, the circulation to the chimney being downward. By the heating of the air in contact with the exteriors ofthe flue J and tube-sheets D D and interiors of the tubes G G, an upward circulation of air from the chamber H through the tubes G G to the chamber E, and thence through the pipes J J, is produced, and a copious supply of cold air enters through the openings a a of the chamber H, to supply the place of what has passed upward.

The air as it enters first strikes the coolest part of the heating-surfaceviz., the lower Y combustion, circulating through theinterstices -lxeats the said luinIs in such a manner that part of the ue J-and as it rises comes next into contact with the hotter surface of the upper part of the said flue, afterward with the still hotter surface of the tube-sheet D, then passes up through the tubes G G, which are hotter toward the top than at the bottom, and finally over the tubesheet D, which is the hottest part of the heating-surface. 1t will thus be seen that the air entering where the heating-surface is coolest passes into contact with gradually-hotter surfaces, and is thus heated in the most eiiective manner.

The lame and gaseous heated products of between the lumps L, of brick or other poor conducting material, between the tubes G G,

they form a reservoir of heat to prevent the sudden cooling of the tubes G G when a fresh charge of fuel has been put on the fire, or from any other cause, and thus prevent sud den changes in the temperature of the heated air delivered into the distributing-chamber E. A reservoir of heat may be formed in a similar manner within the tubes of hot-air fur- Vinterstices between the said lumps or pieces,

substantially as herein specified.

2. The arrangement of the horizontal iiuc C, drop-iiue I, forward-and-backward-circula tion pipe-line J, in combination with each other and with the cold-air chamber H, tubesheets D D', air-tubesG G, and air-distributing chamber E, substantially as herein speci tied.

JOSEPH A. Minnnn.

Witnesses HENRY T. BROWN, J. W. CooMBs. 

